Lung cancer is a common disorder and is a leading cause of death in North Americans. In the United States, each year about 150,000 individuals die from lung cancer. Hospital registry projections indicate that lung cancer mortality in this decade will continue to rise to a rate of over 50 deaths per year per 100,000 population in America. The current lung cancer prevention programs are not expected to have any impact on the death rates until the end of this decade. Lung cancer claims more lives than colon, prostate, lymph and breast cancer combined. Lung cancer has a high incidence world wide. With an increase in smoking, lung cancer rates are steadily increasing all over the Middle East, Africa and Asia.

 

The highest rates of lung cancer in men are found in the Maori population of New Zealand, and in several African-American groups, including the black populations in New Orleans, San Francisco Bay area, Detroit, and Alameda County, Oakland. In addition, the rate of lung cancer remains very high in western Scotland. Yet very low lung cancer rates are seen in the men in the underdeveloped regions of India, Africa, and South America. Surprisingly, non smoking Chinese females also have a very high incidence of lung cancer. This has been linked to the inhalation of vapors from cooking oil, indoor air pollution and exposure to secondary tobacco smoke. Yet most of these lung cancer deaths could be prevented. That's because smoking accounts for nearly 90 percent of lung cancer cases. Although the risk of lung cancer increases with the length of time and number of cigarettes one smokes, quitting smoking, even after many years, can significantly reduce one’s chances of developing the disease. Prevention is critical because lung cancer usually isn't discovered until it's at an advanced stage when the outlook for recovery is poor. Although the survival rates for lung cancer have improved, they remain much lower than those of many other types of cancer.

 

Causes There are several known risk factors for lung cancer: Smoking The number one risk factor for lung cancer is tobacco smoking, which is responsible for more than 80-90% of lung cancers. The more cigarettes that are smoked each day and the younger the age at which smoking begins, the greater the risk of lung cancer. The availability of filter cigarettes and low-tar/low-nicotine brands, have decreased the lung cancer rates, but these rates are still significantly higher when compared to deaths in nonsmokers. The individuals, who quit smoking, also reduce their risk of lung cancer and after 10-15 years, their cancer rate is the same as those who have never smoked. How exactly does cigarette smoking cause lung cancer? This question has not yet been answered definitively. But the most likely cause is the dangerous mix of chemicals found in tobacco smoke. It is known the tobacco smoke contains numerous chemicals all which have the potential to cause cancer. The major chemicals identified in tobacco smoke are polycyclic aromatic hydrocarbons (PAHs), nicotine, nicotine by-products, tobacco-specific nitrosamines (TSNAs), metals such as nickel and cadmium, and radioactive polonium 210. Other chemicals within tobacco may also be responsible for lung cancer. Tobacco contains at least 30 metals, which includes nickel and cadmium – which are known carcinogens.

 

The metals found in tobacco come from the soil, fertilizers, or insecticide sprays. Alcohol Numerous studies have reported a relationship between the severity of alcohol intake and nicotine-dependency, which, in turn, may be controlled by genetic factors. Some researchers suggest that smoking may reduce the intoxicating effects of alcohol and, therefore, may promote the progression from moderate to heavy drinking. The direct association between alcohol and lung cancer has not been discovered yet. Asbestos Asbestosis has long been known to cause lung cancer. There is a synergistic interaction between cigarette smoke and asbestos exposure. It is estimated that asbestos workers with a history of cigarette smoking have a lung cancer risk eight times higher than smokers who have not been exposed to asbestos. In addition, asbestos-exposed male smokers have roughly 50 times the lung cancer risk of nonsmoking, unexposed men. Asbestos is also associated with causing pleural disease of the chest and malignant mesothelioma. This cancer usually arises after 20-30 years after the initial asbestosis exposure. Malignant mesothelioma is lethal and no type of therapy is effective. Diet and Body Mass Recent studies suggest that there is a positive correlation between lung cancer risk and the intake of fat. Some experts suggest that dietary fat consumption may actually modify the association between smoking and lung cancer. In addition, some researchers suggest that dietary intake of vegetables (esp. beta carotene) has a modest, protective effect against lung cancer.

 

The anti carcinogenic (cancer-inhibiting) effect of beta-carotene are of the highest benefit in individuals who continue to smoke or at high risk of lung cancer. Other research suggest that it is not only Beta-carotene that is effective as an anti cancer agent. Some studies have found stronger protective effects from vegetable diets that include cabbages, cauliflower, tomatoes, carrots and sprouts. Second hand smoke exposure There is enough evidence now which indicates that second hand smoke inhalation can cause lung cancer. Over the last several years, there has been a major effort to educate the population about the dangers of exposure to “passive smoking," or "involuntary smoking" (breathing smoke from nearby smokers). It is estimated that approximately one-third of lung cancers in nonsmokers result from passive exposure to cigarette smoke. The smoking bans all over the country have gone a long ways to protect the non smoking public in North America. Occupational Exposure Occupational exposure for those who are exposed to uranium, radon, or asbestos exposure can interact with smoking and cause lung cancer and other lung related disorders. Many individuals who work in the shipping and mining industry are exposed to heavy doses of these chemicals and awareness is required. The mining industry has gone at great lengths to protect the workers from chemical exposure and routine lung examinations for the workers is encouraged. In some countries, environmental pollution is now though to be another cause of lung problems. In china, the incidence of lung cancer is increasingly exponentially and thought to be related to the massive environmental pollution. Increasing age and genetics Lung cancer is more common in individuals over the age of 50. A past history of lung cancer, or a family history of lung cancer, increases the chance of one having lung cancer. Although no strict genetic link has been identified, the chances of having lung cancer are increased if a parent, sibling or other first-degree relative has lung cancer. Radon exposure Radon gas was a major cause of lung cancer some 50 years ago but is not much of an issue today. Radon gas leaks used to be found in certain homes built on areas where radon was leaking in the surrounding. The increased awareness and regulations by the Environmental Protection Agency have almost eliminated radon gas exposure as a cause of lung cancer today. If radon gas is suspected, the best tests are those that take three to six months.

 

Lung Cancer Symptoms and Signs Generally lung cancer has no symptoms in the early stages. Most lung cancers when they have symptoms are usually in the advanced stages. The most common symptom of lung cancer is cough, which can be persistent. In addition other symptoms may include: - blood in the cough - shortness of breath - chest pain - weight loss - joint pains - wheezing - recurrent pneumonias - hoarseness Lung cancers are also known to be associated with features peculiar to cancers only and can cause - muscle weakness - bluish discoloration in the nails - loss of muscle - Weakness - Joint pains and bone tenderness - Excessive calcium - One sided facial paralysis - Eye lid droop Screening There are no screening programs to detect lung cancer. The plain chest x ray is not sensitive enough to identify lung cancers in the early stages and a CT scan is very expensive to routinely screen millions of smokers. Even, the American Cancer Society currently doesn't recommend screening tests for lung cancer, even in high-risk individuals. However, a few physicians around the country have been offering screening radiological tests for high risk patients. These self pay CT scans are postulated to detect lung cancers early in their evolution. However these newer versions of CT scanners are very sensitive and also identify small masses that are often benign. That always leads to unnecessary additional tests and surgery- thus increasing the health care costs even more.

 

Diagnosis Patients who are suspected of having lung cancer should undergo a thorough physical examination. The standard approach to an individual with a suspected lung mass begins with: Chest x ray A standard chest X-ray can reveal an abnormal mass or nodule in the lungs. However, small lung masses are almost never seen on a chest x ray. If a lung mass is seen on a chest x ray, it generally has spread to some extent either in the chest or the rest of the body. The chest x ray may also reveal fluid collection in the chest. It is a very poor test to identify lung cancers. CT Scan The next study after a chest x ray is always a CT scan of the chest. It is very sensitive and can identify lung cancers at an early stage. It can also identify the presence of lymph nodes. A biopsy is always required to make sure that the mass identified is a lung cancer. PET Scan Today, pet scans are available to image the chest. The technique involves the use of radiolabel led sugar and following the localization of this sugar. Since cancer cells are rapidly dividing and take up sugar, the PET scan rapidly identifies the rapidly dividing cells Sputum analysis For those patients who have had a persistent cough with bloody sputum product, the sputum can be analyzed under a microscope and analyzed for cancer cell. The test is not very sensitive and does not always identify the cancer or cancers which are far away in the lung periphery. There are many other causes of blood in the sputum. Bronchoscopy In this test, a flexible tube with a light (a bronchoscope) is passed into the airway. The bronchoscope allows the doctor to look inside the large and small airways. The bronchoscope can also be used to take tissue samples which can be analyzed in the laboratory. Mediastinoscopy In this test, an instrument with a light is passed at the top of the breast bone. The instrument allows one to biopsy lymph nodes in the center of the chest. Lung cancer usually first spread to the center of the chest. If these lymph nodes are positive then the individual has been diagnosed with cancer which has now spread. Most patients who have positive lymph nodes are not candidates for surgery. Transthoracic needle biopsy Occasionally there is a mass seen on chest x ray and a small needle is used to make a diagnosis.

 

The procedure is done in the radiology suite and relatively painless. Thoracentesis Frequently, patients with lung cancer have fluid accumulating in the chest and this fluid can be analyzed for the presence of cancer cells. It involves placing a small needle inside the chest and aspirating the fluid. Removal of the fluid also helps improve the breathing Video thoracoscopy Occasionally a camera with a light is placed in the chest and the lungs are visualized. Through this procedure, small pieces of lung tissue can be obtained for analyses. The procedure is usually done under general anesthesia. The procedure allows one to inspect the entire chest. Blood tests There are no specific markers to indicate the presence of lung cancer. However, some lung cancers do secrete hormones or make excess calcium. So blood tests are done to monitor these parameters. When the lung cancer is removed, the levels of these hormones disappear. Bone scans Many individuals present late to the doctor and complain of pain in the back or the bones. A bone scan is done to rule out the spread of lung cancer to the bone.

 

Lung cancers is notorious for spreading to the bone Stages of Lung Cancer Once a lung cancer has been diagnosed, a process known as staging is performed. This gives the doctor the status of the cancer in terms of its spread. Different stages of lung cancer have different treatment. To identify the stage of the lung cancer, various radiological tests are required. Stage 0 In this stage, the cancer is small and limited to the lung. All lung cancers in this stage are removed by surgery and are considered curable. Unfortunately, it is very rare to find a lung cancer in this stage. Stage I The cancer is larger and involves adjacent lymph nodes only. Cancers in this stage are removed surgically and have a good prognosis. Stage II Cancers in this stage have spread to lymph nodes in the center of the chest. The treatment usually involves chemotherapy and or radiation. Stage III In this stage the cancer has spread from the lung to lymph nodes in the center of the chest, heart, blood vessels, trachea and esophagus — all within the chest — or to lymph nodes in the area of the collarbone. Stage IV In this stage the cancer has spread throughout the body and there is no treatment.

 

Types of lung cancer There are two basic groups of lung cancers: small cell and non small cell. Small cell lung cancer There is a type of lung cancer which is known as small cell lung cancer (oat cell). It is the most aggressive and lethal lung cancer. Because of its extreme aggressiveness and rapid spread, the cancer is staged as either limited or extensive. In the limited stage the lung cancer is limited to the chest, whereas in the extensive stage it is spread outside the chest. Small cell lung cancers grow more rapidly and tend to have spread by the time diagnosis is made. They account for about 20 percent of lung cancers. In general, small cell lung cancer is very aggressive and is treated with chemotherapy and radiation. The majority of patients with small cell cancer are not alive at 5 years despite treatment.

 

Non small cell lung cancer Non-small cell lung cancer is the most common type of lung cancer, accounting for 75% of cases. Non-small cell lung cancer includes squamous cell carcinoma, adenocarcinoma, large cell carcinoma, and undifferentiated carcinoma. These cancers account for more than 75% of all lung cancer. If diagnosed early, surgery is curative. When diagnosed late, the treatment is generally chemotherapy plus radiation. Although great advances have been made in treating lung cancer, more people die of lung cancer than of colon, breast, and prostate cancers combined. Despite new anticancer drugs, better staging and imaging techniques and new surgical procedures the results are still not very promising. There are four major categories of non-small cell lung cancer: Squamous cell carcinoma: This is the second most common cancer and usually found in the center of the lungs. Adenocarcinoma: This type of cancer usually secretes mucus and is found in the periphery of the lung. It's the most common type of lung cancer in women and in non smokers. It may occasionally present like a pneumonia Large cell carcinoma: This type of cancer originates in the peripheral part of the lungs. Bronchoalveolar carcinoma This uncommon type of non-small cell lung cancer tends to grow more slowly than other forms of the disease. It occurs more often in smokers and tends to arise in multiple parts of the lung.

 

Treatment The treatment of lung cancer is highly dependent on the stage and type of cancer. In addition, the patient’s overall health is also an important factor in determining the best treatment. Poor health, bad heart or severe emphysema are all contraindications to surgery.

 

Non-small cell lung cancer treatment Surgery is usually the best treatment for early-stage non-small cell lung cancer. In all cases the entire lobe of the lung is removed to ensure that the cancer will not recur. There are numerous surgical variations along this theme. The surgery is done via a large incision from either the left or right chest. The major morbidity of the surgery is pain along the incision, pneumonia and mild shortness of breath. Any time surgery is done to remove a lung cancer; the lymph nodes are always removed and numbered. The lymph nodes are usually located along the large blood vessels or in the center of the chest (mediastinum). If the lymph nodes are identified as having cancer, this usually indicates that the cancer has spread. In such cases, the patient is usually administered chemotherapy/radiation after surgery. For those cancers which are in the late stages, a combination of chemotherapy, radiation and/or surgery may be used for treatment. Numerous trials are now undergoing to determine the best regimens for treatment of lung cancer.

 

Effects of surgery and recovery For those patients with early lung cancer, surgery can be curative. However, surgery is a major undertaking and involves a large incision on the lateral aspect of the chest. This incision is quite painful and at least 20% of patients complain about the incisional pain for months after surgery. After surgery, the patient requires about 5-7 days in hospital and a 4-6 week recovery period is required afterwards. Physical therapy is highly encouraged after surgery.

 

Small cell lung cancer treatment Because most small cell lung cancers have spread beyond the lungs by the time they're discovered, surgery is usually not an option. Instead, the most effective treatment is chemotherapy, either alone or in combination with radiation therapy. Chemotherapy involves the use of potent drugs which kills rapidly dividing cells. Usually a combination of drugs are administered over a period of 6 weeks. Unfortunately these drugs are not always selective for cancer cells and also affect normal cells. Thus, the majority of patients do develop some sort of side effects. These side effects may range from nausea, vomiting, hair loss, poor appetite, diarrhea infections of the mouth, recurrent pneumonias and fatigue.

 

Small Cell Lung Carcinoma (Limited-Stage) For the limited stage small cell cancer, standard treatment programs include a combination of chemotherapy with or without prophylactic cranial (head) irradiation.

 

Extensive-Stage Small Cell Lung Cancer (SCLC) For those with extensive stage small cell cancer, the treatment involves combination chemotherapy, with or without prophylactic cranial irradiation (PCI), individuals with metastatic lung cancer who are in poor health or have significant co- morbidity should only be considered for palliative/comfort care. For all other higher stage SCLC patients, chemotherapy is a suitable treatment option, since it may prolong survival. However, the choice of chemotherapy should take into account factors such as the goal of therapy, possible complications of the therapy and whether survival can be prolonged.

 

Radiotherapy (Radiation Therapy) Radiotherapy is frequently used in the treatment of lung cancer. The aim of the treatment is to prevent recurrence of the cancer. The treatment uses high-energy, ionizing rays to kill cancer cells. Ionizing radiation are generated by a number of radioactive elements. Radiotherapy can cause a shrinkage of the cancer which can than be removed by surgery. Radiation therapy can also help decrease the symptoms and may help to relieve the pain from cancer. The treatment is given over a period of 6 weeks. The protocols for administering radiation therapy varies and may be given before or after the chemotherapy. Radiation therapy can also be delivered to when lung cancer has spread to the bones. In particular, radiation may be directed at cancer metastases in the vertebral column and bones. Patients with severe lung emphysema may not be candidates for radiation therapy. The side effects of radiotherapy include hair loss, skin reddening, itching, and dryness of skin, hard leathery skin, shrinkage, edema or swelling. Radiation can also cause quite pronounced changes in taste perception, nausea, vomiting and general malaise.

 

Prophylactic cranial irradiation Because lung cancer has a propensity to spread to the brain, frequently radiation treatment is administered to the brain. Cranial radiation can decrease the risk of developing brain metastases in patients with lung cancer. Some oncologists believe that prophylactic (before the cancer has spread) cranial radiation is helpful; whereas others suggest that a "watch and wait" approach is more practical. Neither of these have made an impact on survival. The need for cranial radiation is best determined by a discussion between the physician and the patient. Individuals should be aware that radiation to the brain can cause destruction of parts of the brain (leukoencephalopathy or leukodystrophy). The brain degeneration occurs about 12 months after the radiation and can present as loss of memory, forgetfulness, awkward movements and confusion.

 

Photodynamic therapy (PDT) PDT is an option when the individual is not a candidate for surgery or the cancer may be in the very early stages. The technique requires the administration of a chemical which is activated by light (photofrin/polyhaematoporphyrin). The chemical sensitizes the cancer cells and then a laser is used to destroy these sensitized cancer cells. A common side effect of this therapy is that numerous individuals develop sensitive to sunlight. The chemical leeches out into the skin and when sunlight exposure occurs, the skin blisters or becomes red. This therapy is not first line and may be used in combination with other therapies.

 

Electrosurgery Electrosurgery is another technique used to treat patients who are not candidates for complete removal of the cancer. The procedure involves placement of a probe/needle into the tumor and then either laser or radiation is used to destroy the cancer mass. Other modifications of this therapy involves use of Cryotherapy (cooling the cancer cells) or brachytherapy (placement of small needle tip radioactive implants in the cancer cells. All of these techniques are considered palliative and not first line therapy. These techniques can help reduce the tumor size and decrease the symptoms.

 

Prognosis Unfortunately, most lung cancers are diagnosed very late and thus are almost always spread by the time diagnosis is made. Very few lung cancers are identified in the early stages where surgery can be curative. Without treatment, most patients are dead within 6-12 months. Even with treatment, the best prognosis is for patients in the early stages and receive prompt treatment. For those who present in the late stages, even with treatment, less than 25% are alive at 5 years. Unlike non small cell lung cancer, small cell cancer is usually treated with chemotherapy and radiation therapy. Recent data indicate that very early stages of small cell lung cancer may infact be better treated with surgery. Overall, fewer than 10% of people with primary lung cancer are alive 5 years after diagnosis. But 5-year survival rates have been improved to 30-35% in patients who have undergone surgical resection for limited lung cancer. Recent advances in chemotherapy have improved survival of patients with small cell lung cancer. Recent data indicate about 50% of patients who have been treated aggressively are alive after 2 to 3 years. By contrast, untreated patients with localized disease rarely survive beyond 3-4 months.

 

Newer therapies for small cell cancer A number of recent clinical trials have examined the treatment of small cell lung cancer. Recently some of the most interesting approaches are treatments with biological modifying agents such as monoclonal antibodies (immune system molecules), newer chemotherapeutic agents; new radiation therapy schedules; new radiation techniques and improved timing of chest radiation. Various drugs have been developed that work at the molecular level and inhibit the growth of cancer cells. Two of these drugs include Erlotinib and Bevacizumab. Erlotinib is currently approved in the treatment of lung cancer in combination with other therapies. Preliminary findings suggest that these newer therapies may prolong life in some patients with small cell lung cancer.

 

Follow up All patients who undergo surgery/chemotherapy need proper follow up to ensure that the cancer does not return. Period Chest X rays and Ct scans are obtained for the first few years and regular follow up with an oncologist are recommended.

 

Treating advanced non-small cell lung cancer Because of the dismal results with advanced lung cancer, numerous trials with newer protocols are being undertaken at most large cancer centers. Depending on the protocols, patients with advanced non-small cell lung cancers are generally treated with chemotherapy, radiation, or a combination of both chemotherapy and radiation. Despite set protocols, individual variation in treatments are common. One may involve in various clinical trials but one should fully understand that the result of cure are not guaranteed with clinical trials, however, one should fully understand the potential risks as well as possible benefits before enrolling in any clinical trial.

 

Prevention The best prevention to lung cancer is not to smoke. For those who smoke and quit, the risk of lung cancer significantly decreases annually. Other measures that may help include: - Avoidance of secondhand smoke. Data indicate that breathing second smoke is just as serious as smoking - Radon gas. Radon gas is no longer an issue today unless one lives in an area where radon gas has been a problem. - Eat healthy. Healthy eating is beneficial for overall health.

 

Self-care Unfortunately, life is finite and sometimes cancers occur without the presence of any risk factor. The best advice is to lead a healthy life style, eat right and exercise regularly. This regimen is useful for a healthy and disease free life. If cancer still occurs after this, then one just has a lot of bad luck.